1. Field of the Invention
The present invention relates in general to an optical image transfer system, and more particularly to a technique that permits the use of a simple, small-sized light source for the image transfer system.
2. Discussion of the Prior Art
There is known an image transfer system of a type wherein images are formed on a photosensitive medium by exposure of the medium to a radiation. For example, such a photosensitive medium consists of a substrate, a developer layer formed on the substrate, and a layer consisting of a multiplicity of microcapsules that are formed on or embedded in the developer layer. Each microcapsule includes a radiation-curable photosensitive resin, a normally colorless chromogenic material (color former which becomes a dye) which reacts with the developer layer to form a visible image spot, and a photoinitiator for promoting polymerization of the chromogenic material. Upon exposure of the photosensitive medium to a radiation, the radiation-curable resin of the microcapsules in exposed areas of the medium is polymerized and thus hardened to an extent corresponding to an amount of exposure to the radiation. On the other hand, the radiation-curable resin of the microcapsules in unexposed or insufficiently exposed areas of the medium remain uncured or are insufficiently cured. The microcapsules in the uncured or insufficiently cured areas are ruptured in a subsequent developing process wherein the photosensitive medium is pressed, heated or subjected to a chemical treatment. As a result, the chromogenic materials come out of the ruptured microcapsules and react with the developer layer, producing visible image spots on the photosensitive medium, according to the amounts of the chromogenic materials which have reacted with the developer layer.